Endangered white-clawed crayfish are being painstakingly moved as a Northumberland river is restored to its original course.
The River Wansbeck at Mitford has been diverted for a year to allow a flood storage dam to be built to protect Morpeth.
But this week, it is being reinstated along its original route.
Before the river was redirected, workers first had to check for white-clawed crayfish - the only crayfish species native to the British isles - in the temporary 100-metre channel.
The Environment Agency had relocated the endangered creatures to a safe new home upstream of the dam before the Wansbeck was moved last year.
But some had moved downstream into the channel over the intervening months - so workers had to carefully move them to safety once again before the stretch is closed off and refilled.
Anthony Myatt, project manager at the Environment Agency, said: “The diversion of the Wansbeck was vital to allow the construction of the flood storage dam, and now we are at the important stage of directing it back under the new dam.”
The dam, built as part of the Morpeth flood protection scheme, has also seen a number of culverts built along the Wansbeck’s course.
When heavy rainfall increases the water level in the river, the culverts restrict the amount of water that is able to flow downstream through Morpeth, reducing flood risk to the town.
The culverts within the dam walls feature special channels that allow fish, crayfish and lamprey to travel upstream.
“The culverts at the bottom of the dam will control the rate of flow of the river in times of high rainfall, keeping the river at a safe level in Morpeth,” Mr Myatt added.
“This key feature of the town’s flood defence scheme is complemented by improved flood defences in the town itself.”
Once the river has been diverted to its original course, the Environment Agency will be able to start the earthworks to build the dam embankment.
On Monday, Morpeth residents, emergency services and volunteers took part in a training day to test out the town’s new £27m flood defences and community flood plan, brought in after the town was devastated by flooding in 2008 and 2012.
The live exercise started with messages sent to the town council from the Environment Agency about expected ‘heavy rain fall’.
When the water rose to a ‘critical level’, the council contacted a team of volunteers who put into practice the new action plan called the Morpeth Community Agreement and shut three flood gates at High Stanners and evacuated homes of residents.
The £27m Morpeth Flood Alleviation Scheme - which is now £5m over budget - involved building a new flood defence wall and three flood gates in High Stanners which protect homes.
The Environment Agency said people have been given flood protection devices like metal shutters to use on their doors.